Someone who uses their poon-tang as bait and reels you in with latent promises of them letting you poon their tang who then relocates their tang to a un-poonable location... so while their tang isn't necessarily un-pooned you certainly aren't the tanger.

(Adj.) A word used to describe the smoothness or coolness of an action, phrase, or anything in general.
(Noun) A trick that can be performed on a skateboard, snowboard, or any variation of the two. It consists of moving of the feet in the air, creating a "shift".

A Shifty is a person that thinks he's the best, blames other people for his mistakes and doesn't understand that people do not always have time for him of things he's busy with. He generally gets mad at the people he doesn't understand.

Me: Hey, I can't make it tonight, sorry. (For let's say: Battlefield clan war)
Shifty: Then just don't come back idiot, we don't even need you anyways.
Friend: Why does he have to be such a Shifty?